Argus Filch is the caretaker at Hogwarts. He has a pet cat called Mrs. Norris who is usually on the prowl, keeping an eye out for him. He is bitter, cruel and seems to hate the students. He seems to work well with oppressors, seeing their use of rules as only natural and correct; he would be a perfect tool for a totalitarian regime. Every year he asks Dumbledore to read out what is banned. An example of things that are banned are Fanged Frisbees and, later, Weasleys' Wizard Wheezes products.

Harry and Ron get off on the wrong foot with Filch on the very first day of classes when he catches them trying to enter the forbidden corridor. They had not meant to visit that corridor; they had simply gotten lost on the way to Transfiguration class. They are saved from being locked in the dungeons by Professor Quirrell, who happens to be passing by.

At tea with Hagrid on the Friday of their first week, Harry is pleased that Hagrid refers to Filch as "that old git". Hagrid also says that he can't abide Mrs. Norris, and that Filch has apparently instructed Mrs. Norris to follow Hagrid around.

Shortly after this, Draco Malfoy challenges Harry to a Wizard's Duel. Harry and his second, Ron, followed by Hermione and Neville Longbottom, go to the Trophy Room, the designated site for the duel, but instead of finding Draco there, they hear Filch approaching. Trying to escape, Neville knocks over a suit of armour, and in the ensuing mad dash to escape they end up in the forbidden third floor corridor. Peeves has followed them as far as the door, but decides in the end that it would be more fun to taunt Filch than it would be to lead him to the four, thus allowing them to escape.

Trying to retrieve the copy of Quidditch Through the Ages that Harry had taken out of the library, and that Professor Snape had confiscated, Harry looks into the staff room, where he finds Filch binding up a wound on Snape's leg. Snape is incensed that Harry has seen this injury.

Harry receives an Invisibility Cloak for Christmas, and trying it out that night, opens a book in the Restricted Section of the library. The book starts screaming, and Harry runs, ducking under Filch's arm as Filch, wild-eyed, enters the Library. When Harry pauses for breath, he is alarmed to realize that, despite the distance he has traveled, Filch is approaching, saying that someone had been in the Restricted section. Harry is further dismayed to discover that the person Filch is talking to is Snape. The corridor is so narrow that the two of them won't be able to get past Harry, so Harry retreats though an open doorway, finding himself in a disused classroom containing the mirror of Erised.

When Hagrid's baby dragon, Norbert, is sent away, Hermione and Harry forget the Invisibility Cloak at the top of the tower. Filch catches them as they descend back into the school. Some time later, Filch escorts them, with Neville and Draco, who have also received detentions, over to Hagrid's, where they will be assisting Hagrid in searching for something that is killing unicorns.

At the Entrance Feast, Professor Dumbledore mentions that "our caretaker, Mr. Filch", has banned certain items; the full list of banned items is posted on his door.

Harry and Ron have received detention for driving a flying car into the Whomping Willow; at the end of the first week of classes, Professor McGonagall tells them that Ron's detention will be served with Filch, polishing the trophies, while Harry will be helping Gilderoy Lockhart answer his fan mail. Ron later says that he had a recurrence of the jinx he had tried to cast at Malfoy, and belched up a great lot of slugs on a Special Award for Services to the School, which he had then had to polish about ten times to get the slug slime off.

The Autumn weather is dismal and wet, and Harry, coming in from Quidditch practice, is sodden and muddy. Stopping to talk with Nearly Headless Nick, he is surprised by Filch's cat, Mrs. Norris, and, before he can make his escape, Filch himself. Filch, enraged, hauls Harry off to his office, where he begins writing him up for "befouling the castle". He is interrupted, however, by a loud crash from upstairs; shouting "Peeves!" he rushes off. Harry, left on his own, finds a letter from a company called "Kwikspell" on Filch's desk; looking at it, he sees that it is full of testimonials from people who say that the Kwikspell course had taught them magic when they had been unable to do any before. Harry, hearing Filch returning, puts the letter back on his desk. Filch returns, seemingly pleased: apparently Peeves has dropped a very valuable Vanishing Cabinet, and Filch seems to feel that this will compel Dumbledore to evict Peeves. Filch notices that the Kwikspell letter has been moved; he quickly shuffles it out of sight, then, looking embarrassed, tells Harry that he's free to go.

At Hallowe'en, Mrs. Norris is found Petrified and hanging from a torch bracket, near words scrawled on the wall: "The Chamber of Secrets has been opened. Enemies of the Heir, beware!". Enraged, Filch says that Potter has something to do with it, because he was in the vicinity at the time. Professor Dumbledore, arriving, takes Mrs. Norris off the torch bracket, and in company with Filch, Professor Snape, Professor McGonagall, Gilderoy Lockhart, Harry, Ron, and Hermione, carries her to Lockhart's office where he examines her. While it turns out that she is not dead, Dumbledore is unable to suggest how she was Petrified. Filch says that Harry must be involved, because he knows that Filch is... a Squib. Filch demands that someone be punished; Snape suggests that Harry must know more about things than he is telling, and suggests suspending him from the Quidditch team, a suggestion which McGonagall immediately resists. Professor Dumbledore reminds everyone that Harry is innocent until proven guilty, and tells Harry, Ron, and Hermione that they are free to go. Ron later explains why Filch was so upset; a Squib is a child of magical parents who is unable to do magic himself.

Over the next several months, we often see Filch wandering the hall trying to give students detention for "acting cheerful" or "breathing too loudly", sitting in a chair immediately under the torch bracket where Mrs. Norris was found, or trying to scrub the writing off the wall. Shortly after Christmas, Harry and Ron hear an outburst from Filch; peering around the corner, they find that he has abandoned his usual station, which turns out to be right outside Moaning Myrtle's bathroom, because Myrtle has turned on all the water and is flooding the hall. Investigating, Harry and Ron discover that someone has thrown a diary down a lavatory, and Myrtle is upset because it went through her head.

Filch does not play much more of a role in this book, but we do see him briefly at the end of the book when he is re-united with Mrs. Norris.

We don't see a lot of Filch in this book. At the first Hogsmeade weekend, Filch is checking people against a long list of names to see if they have permission to visit the village; Harry, not having permission, watches Ron and Hermione pass him, and then returns to Gryffindor tower. On the way, he is intercepted by Fred and George Weasley, who show him the Marauder's Map, a magical map that shows where everyone is in the castle. They say that they had stolen it from Filch's files once when they were being written up for setting off Dungbombs in the halls, but seeing how much greater Harry's need is than theirs, they give it to him, with instructions how to use it. This map is Harry's ticket to Hogsmeade, as it shows secret passages out of the school.

Filch is also present at Christmas dinner, and apparently it is rather ghastly watching him try to have a good time.

Filch's role in this book is again minor. Harry notes that he is setting out extra chairs at head table at the feast celebrating the arrival of the two additional schools for the Tournament; Ron wonders why four chairs, as the only two guests that they know about are Madam Maxime from Beauxbatons, and Igor Karkaroff from Durmstrang. Ron's question is answered when Professor Dumbledore introduces the other two judges for the Triwizard Tournament, Ludo Bagman, and Bartemius Crouch. Shortly afterwards, Dumbledore asks Filch to bring out the casket that holds the Goblet of Fire.

When Harry, acting on a hint given to him by Cedric Diggory after the Yule Ball, visits the Prefects' Bathroom to try to decipher the clue in the Egg, he uses the Marauder's Map to see where Filch and Peeves are before venturing into the hallways. He checks again before heading back to Gryffindor Tower, and as he is doing so, he sees Bartemius Crouch in Snape's office. He chooses to investigate; getting his foot caught in a trick step, he drops the egg which immediately starts wailing. This summons Filch and, shortly, Snape. Filch believes that Peeves has stolen the Egg from one of the Champions and dropped it. Snape dismisses this concern, saying that someone has been in his office, and it must have been a wizard because of the charm he put on his door. The presence of the egg convinces Snape that Harry is there under his Invisibility Cloak. Professor Moody's arrival prevents Snape from finding Harry, and Moody sends both Snape and Filch on their separate ways before rescuing Harry from the trap he has gotten himself into.

Harry's scar pains him at the end of one of his sessions of detention with Dolores Umbridge, and he feels a need to write to Sirius Black, his godfather, to tell him about this. As he heads for the Owlery to mail the letter, he is spotted by Mrs. Norris. He is joined in the Owlery by Cho Chang, who is mailing off a birthday present for her mother. As they are talking, Filch bursts in, accusing Harry of preparing to mail off an order for Dungbombs. He demands to search Harry's pockets, but Cho defends him, saying that whatever it is, Harry had already sent it, she saw him.

When Harry heads to Hogsmeade for the next Hogsmeade weekend, Filch sniffs at him suspiciously; evidently he is carrying through on his threat in the Owlery that he will be watching for any scent of dungbombs on Harry. Harry mentions the episode in the Owlery to Ron and Hermione, wondering why Filch would have though that he would order Dungbombs. Hermione wonders who had tipped Filch off, and suggests that it might have been a ploy to get a look at Harry's mail.

When Hedwig returns with Sirius' answer, she has been attacked, and possibly the message that she carries has been read. This seems to confirm Hermione's suspicion that Filch had been instructed to try and read Harry's mail.

Shortly after Dumbledore leaves and Umbridge is appointed Headmistress, she asks Filch to summon Harry to her office. Filch is ecstatic, talking about how things will change now she's in charge. Umbridge has apparently told Filch that she is in favour of corporal punishment, and will be arranging to have Peeves evicted. Having told Harry all this, he announces Harry at Umbridge's door and then departs.

As Harry's interview with Umbridge is about to end, a series of explosions sounds in the main stairs. Umbridge and Filch run to investigate, but are powerless to handle the fireworks which Fred and George have set off. Having unsuccessfully tried to charm one of the fireworks away, Umbridge instructs Filch not to use magic against them; Harry is amused by this as he recalls that Filch, being a Squib, can't use magic anyway. Filch's attempt to dispose of a firework by hitting it with a broom is also unproductive, resulting only in a burning broom.

After Easter break, Fred and George become aware that Harry has need of Umbridge's fireplace, which is the only safe route he knows of to contact Sirius. They tell Harry that they are going to set off a diversion at 5PM. Though Hermione repeatedly advises against it, Harry decides to make use of the diversion to talk to Sirius. As he is speaking with Sirius, Harry hears someone entering Umbridge's office; hiding under his Invisibility Cloak, he watches as Filch enters the office and locates the forms to authorize whipping. Following Filch, Harry finds the twins, trapped by Umbridge in the Entrance Hall. Filch presents Umbridge with the necessary paperwork, and the twins, saying that they have had enough formal education, Summon their brooms and depart Hogwarts.

The diversion turns out to be a swamp, which now fills an entire corridor. Umbridge is unable to remove it, and the other teachers seem disinclined to try, so Filch is given the additional duty of taking students to their classes by punt. Additionally, in Fred and George's absence, many students are trying out for the role of chief troublemaker, and the halls are overwhelmingly redolent of dungbombs and stink pellets. Filch, along with Umbridge and her Inquisitorial Squad, are run ragged trying to catch troublemakers.

Presumably, Filch's life gets somewhat easier once Umbridge is fired, however, we don't hear of him again in this book.

Filch's role in this book is again diminished. We do hear from him that he feels that Umbridge is the best head Hogwarts has ever had; he seems to have forgotten the little matters of the swamp in the fifth floor corridor and the epidemic of dungbombs and stink pellets.

We hear that Filch has imposed a blanket ban on all products of Weasleys' Wizard Wheezes, and is scanning everyone who goes in and out of the school with Secrecy Sensors. He scans the Trio as they depart for their first Hogsmeade weekend. As they return, they are following behind Katie Bell, when she is Jinxed by a necklace she is carrying for someone at the school. Harry finds Hagrid to help get Katie back to school where she can be helped, and, carrying the necklace, follows. Meeting them at the school entrance, Professor McGonagall relieves Harry of the necklace, giving it to Filch to carry to Professor Snape.

Discussing this later, the Trio wonder exactly what was intended. With Filch scanning everything with his Secrecy Sensor, it is very unlikely that the package would have made it into Hogwarts, much less reached its eventual destination.

As Christmas, and Horace Slughorn's Christmas Slug Club Party, approach, Harry is the target of a large number of girls angling for invitations to the party from Harry. Hermione warns him to be careful of girls offering him things, they might well conceal love potions. Harry asks how they could get through Filch's secrecy sensors? Hermione points out that there isn't anything particularly Dark about love potions, and simply concealing them in perfume bottles, a service offered by Fred and George, would be sufficient to hide them.

Harry attends Slughorn's party with Luna Lovegood. Halfway through the party, Draco Malfoy is dragged in by Filch. Filch had caught him wandering the halls; Slughorn assumes that he was trying to gatecrash his party, and magnanimously invites him to join, to Filch's evident dismay. Draco and Snape, who is also present, very shortly manage to leave the party for a private discussion.

After Ron's birthday, at which he was first dosed with Romilda Vane's love potion, and then poisoned, Harry and Hermione leave the Hospital Wing with Hagrid to allow Ron's family to be with him. Hagrid mentions an angry conversation between Snape and Dumbledore which he had overheard, and Harry and Hermione are pressing him for more information when they are interrupted by the arrival of Filch, who is annoyed at students being out of bed at midnight. Hagrid angrily says that they are with him, a teacher, and as the quarrel starts to get loud, Harry and Hermione escape.

Harry interrupts Draco Malfoy when he is talking to Moaning Myrtle, and Draco retaliates by trying to hit Harry with the Cruciatus curse. Harry, in self defence, casts Sectumsempra. He is given detention for using Dark magic, and his detention is to recopy Filch's files that are beginning to deteriorate. These files have been specifically selected by Snape so that they include details of Harry's father's wrongdoings.

As almost none of the action in this book occurs in Hogwarts, we do not see very much of Filch. His appearance seems to be limited to a single cameo immediately before the first Battle at Hogwarts, where, much to his dismay, he is ordered to find Peeves and bring him to Professor McGonagall. We are told that he will be supervising the evacuation of the under-age students from Hogwarts, however.

Through long residence in the castle, Filch knows pretty nearly everything there is to know about the physical layout of Hogwarts, and he is able to reach any location in the castle, from anywhere, almost immediately. Between himself and Mrs. Norris, Filch seems to be aware of everything going on in the castle, particularly if it is something forbidden.

Argus Filch is a Squib, a child of wizard parents who has the inability to use magic. Harry discovers this in Harry Potter and the Chamber of Secrets when he spies Filch's "Kwikspell" letter, although he does not understand what that means until Filch says in front of him and Ron, "He knows I'm... I'm a Squib!" Even then, it is only when Ron explains what a Squib is that Harry understands the true significance of the Kwikspell letter and why Filch was so sensitive about it.

His lack of magical ability has made Filch singularly unsuited for almost any work available in the wizarding world; the caretaker position at Hogwarts is likely the only occupation available to him. Seeing this endless parade of wizarding children entering, gaining the skills he will never have, and leaving for a life he can only dream of, has left him bitter. This bitterness expresses itself in the endless restrictions he places upon the students and the powerful desire he has to torture them.

The author has stated that the Kwikspell course does not work for Filch; he is doomed to remain a Squib for all his life.

Argus Filch has a lieutenant, his cat. Mrs. Norris is described as almost skeletally thin and dust-colored, and is apparently able to detect wrong-doing and report back to Filch, whereupon he appears on the scene to deal with the wrong-doer. She may be a magical cat-like animal known as a Kneazle, or like Crookshanks she may be a cat / Kneazle crossbreed. While many of the students have expressed a desire to harm Mrs. Norris for reporting their actions to Filch, she has never yet come to harm by a student. However, she was petrified by the monster from the Chamber of Secrets. Filch was desolated by her absence for the seven months before she was restored.

Filch is perpetually in a bad temper, and many of the deeds that he prosecutes students for are quite minor: he attempts to "write up" Harry for the unforgivable crime of dripping mud on the floor. This over-authoritative adherence to rules, many of which he makes up himself, has made Argus Filch an object of mild derision among the teachers, and widely disliked by the students.

In Dolores Umbridge, Filch seems to find a kindred spirit: it seems they both hate the students equally, and once she becomes Headmistress, Umbridge seems to be willing to allow Filch to start torturing the students. Filch seldom seems happier than when he is doing Umbridge's bidding.

It has been suggested that Irma Pince and Argus Filch have a relationship, by many fans, and in fact by Harry and Ginny in conversation. There is no evidence supporting this relationship anywhere else in the series (other than their standing together at Dumbledore's funeral), though they do seem to share a similar outlook on life and the students.

Mrs. Weasley tells us that Filch's predecessor was named Apollyon Pringle. Pringle had caught her and Arthur returning to the school after a 4AM stroll; apparently Mr. Weasley still bears the scars from that encounter.

As is so often the case, the author is playing to a certain extent with classical mythology. In this case, the name "Argus" is likely selected from the mythical guardian with a thousand eyes. Given Filch's apparent awareness of all "malfeasance" within the school, this seems quite a reasonable parallel.

Intermediate warning: Details follow which you may not wish to read at your current level.

It's certainly true that an establishment the apparent size of Hogwarts, occupied by that large a number of students, is going to need more than a single housekeeper; with magic, it would be possible, but the amount of space a single non-magical person can keep clean would be far less than the precincts of a castle. This is not helped by the teachers propensity to have their classrooms at the extreme ends of the castle - the Astronomy Tower, for instance, and Professor Trelawney's classroom at the top of the castle, and Professor Snape's classroom in the dungeons; nor can it be helped by the dormitories being similarly spread out, with Ravenclaw and Gryffindor in towers and Slytherin in a dungeon. It's only in the fourth book that we are informed that the castle also employs a large number of house-elves, who are charged with much of the domestic work including cleaning.

Given that the cooking, cleaning, and probably (to a large extent) mending is handled, what is the purpose of having a human housekeeper? We surmise that the main reason for the existence of the office is to manage the house-elves and maintain control over the students. House-elves would see students as "masters", as they see any human associated with the house that employs them, and so would allow the students to run riot. Additionally, a human overseer could be given instructions like "Maintain order, and keep the place clean," and would be able to break that down into suitable duties for the house-elves, presumably for other assistants like the portraits and the armor, in ways that these less-capable assistants could not. Additionally, a human would have the necessary authority to keep the students in line at times when the teachers were not available. Quite possibly some of this character goes back to the author's own childhood in grade school, where the janitor was a scary being simply because he was unknown.

So why Filch, why a squib in this important position where he might have to be dealing with magical children? We believe that in the series as a whole, this is in part meant to cast some light on Dumbledore's character. We know that Dumbledore has hired other squibs, notably Arabella Figg, and believe that this is a conscious choice on the part of the author to show that Dumbledore is particularly open-minded towards those who are unable to perform magic.